Development of New Design Guidelines for Protection against Erosion at Bridge Abutments – Phase II

Severe floods in the United States Midwest have caused major erosion at bridge abutments despite the fact that their protection design measures followed existing guidelines (e.g., Hydraulic Engineering Circular No. 23, 2001 and following updates through 2009). One likely possibility for the severe bridge erosion observed especially at small bridges is that the methodology to estimate the variables in the design formulas (e.g., for the minimum size of the riprap stone used for protection) recommended in these guidelines is oversimplified and/or does not account for complexities associated with these structured being placed in natural streams where, for instance, bank curvature effects may be important. The present research proposes a numerically-based approach for improving methodologies to design riprap protection measures at wing-wall and spill-through abutments. The mean flow fields and the bed shear stress distributions are obtained from fully three-dimensional, non-hydrostatic RANS simulations. These data are used to estimate the maximum bed shear stress over the riprap layer, the shear-failure entrainment threshold for the riprap stone and the other variables in the design formulas recommended in HEC 23 (Lagasse et al., 2001, Pagan-Ortiz, 1991). The numerically-based approach was validated for the case of wing-wall abutments placed in a straight channel based on data from laboratory experiments. The present Year 2 report describes how channel curvature and floodplain width affect the maximum bed shear stress over the region protected by riprap for wing-wall abutments placed at the two sides of a channel containing a floodplain at its two sides. A modified, two parameter, design formula is proposed that explicitly incorporates the effects of bank curvature and floodplain width.

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  • Supplemental Notes:
    • This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program. Supporting datasets available at:
  • Corporate Authors:

    University of Iowa, Iowa City

    Department of Civil and Environmental Engineering
    Iowa City, IA  United States  52242

    Mid-America Transportation Center

    University of Nebraska-Lincoln
    2200 Vine Street, PO Box 830851
    Lincoln, NE  United States  68583-0851

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
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  • Publication Date: 2020-1


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 51p

Subject/Index Terms

Filing Info

  • Accession Number: 01747797
  • Record Type: Publication
  • Report/Paper Numbers: MATC-UI: 141-1, 25-1121-0005-141-1
  • Contract Numbers: 69A3551747107
  • Created Date: Aug 7 2020 4:49PM